Right, what I meant was that net size is bigger BUT process is getting smaller and density of elements rises leaving any possible channel dims extremely small.
For CPU to work it has to be an intgral structure so it is not possible to create micro channels between layers of circuitry. Having die microchanneled on external surfaces is counter productive and makes no sense.
Even if it was possible/feasible to make a die wirh layer of circuitry stacked on each other with micro dim spacing inbetween with some sorft of interface connecting them (uff, nice bit of SF going on here) then amount of coolant types described by you needed to pass through to achieve any cooling would
call for extremely high pressures (to maintain coolant's velocity or mass flow in time through changing diameters of a vessel pressure needs to change - some basics here for ya d00de) = kaboooom and flying silicone
Read about thermoelectrics and use of electrons themsleves for cooling and go down to nano level of architecture
Skimmed over your linky. It looks like an attempt at direct die phase change cooling using premanufactured on-die-surface-microfinns... I could not understand why did they limit themselves by putting a glass cover on top of this channels severely limiting the amount of coolant to be boiled and they use sequential flow pattern.... then check page 35 for test results - useless performance for current CPUs thermal output
Nice find anyway, I hope I'll fbe able to find some time to read it all